The invention relates to peeling apparatus and, more particularly, to roller-type shrimp-peeling machinery.
Originally introduced because of the high labor costs of peeling small shrimp by hand, shrimp-peeling machines are now widely used in the shrimp-processing industry. Roller-type peeling machines, in particular, dominate the bulk shrimp-peeling industry. U.S. Pat. Nos. 2,778,055, Jan. 22, 1957, and 2,537,355, Jan. 9, 1951, both to Fernand S., James M., and Emile M. Lapeyre, describe the basic structure and principles of operation of roller-type shrimp peelers.
In the upper peeling sections of conventional roller-type peelers, a series of small diameter stainless steel insert rollers rest between and on a rubber-coated upper power roller and an adjacent rubber-coated lower power roller vertically and horizontally offset from the upper roller. The insert rollers are rotated by contact with the rubber-coated rollers. Peeling nips are formed between the insert rollers and the lower rollers. The rollers rotate continuously in one direction and then the other to grab and release shrimp urged down the lengths of the rollers by a stream of water and gravity. The insert rollers are held down in the notches between the larger-diameter upper and lower power rollers by holddowns. As shown in FIG. 9, conventional holddowns 154 include a narrow strap 156 that fits through the narrow space between the lower and upper rollers and that has a hooked portion 158 at one end encircling and retaining a cylindrical stainless steel pin 160. Springs attached between the peeler frame below and holes 162 in the straps bias the holddowns into contact against the rubber-coated rollers. The insert rollers 164 are made of stainless steel and have axial bores 166 formed in each end. The bores are lined with a bronze bearing sleeve 168. The holddown pins are received in the bores. The insert rollers rotate on the pins with the bronze bearing sleeves providing a low-friction bearing surface to the stainless steel pins.
When a conventional insert roller is new, as in FIG. 10A, the holddown pin 160 rests on the bearing sleeve 168 in the bottom of the bore of the insert roller 164. The contact area between the pin and the sleeve is relatively broad. (In both figures, the diameter of the pin is exaggeratedly small relative to the diameter of the bore for better viewing.) As the bronze bearing sleeve wears, however, as shown in FIG. 10B, the contact area decreases to close to an axial line of contact 171 along the bottom of the bore 166. Furthermore, because the bottom of the bronze bearing has largely worn away, the stainless steel pin 160 bears directly on the stainless steel bore wall 172 of the insert roller 164. This stainless-on-stainless contact increases friction and can cause galling.
The depth of the bore 166 in the insert 164 is greater than the distance of the blunt ends 174 of the pin from the side 175 of the hooked portion 158 of the holddown, as shown in FIG. 9. This makes it possible for the insert rollers 164 to contact the sides 175 of the stainless steel hook portion 158 of the holddowns 154. The rotation of the insert on the hooked portion produces an annoying squeaking sound, as well as an increase in friction.
Thus, there is a need for a less noisy peeler with longer lasting insert rollers and holddown pins.